Remove support for custom overscroll background

cc/trees/layer_tree_host.h

Index: cc/trees/layer_tree_host.h
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index 9069b9d97d6710bf32c384f8de0aca3a3700221d..fa3e6e1813d0900e20511ee32b361ed33e201f0c 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -232,8 +232,6 @@ class CC_EXPORT LayerTreeHost {
     has_transparent_background_ = transparent;
   }
 
-  void SetOverhangBitmap(const SkBitmap& bitmap);
-
   PrioritizedResourceManager* contents_texture_manager() const {
     return contents_texture_manager_.get();
   }
@@ -438,10 +436,6 @@ class CC_EXPORT LayerTreeHost {
   SkColor background_color_;
   bool has_transparent_background_;
 
-  // If set, this texture is used to fill in the parts of the screen not
-  // covered by layers.
-  scoped_ptr<ScopedUIResource> overhang_ui_resource_;
-
   typedef ScopedPtrVector<PrioritizedResource> TextureList;
   size_t partial_texture_update_requests_;